.shadow {
    background: #000;
    filter: alpha(opacity=70); /* IE的透明度 */
    opacity: 0.5; /* 透明度 */
    display: none;
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    z-index: 965; /* 此处的图层要大于页面 */
}

.login-box {
    text-align: center;
    width: 500px;
    height: 350px;
    border-radius: 10px;
    /*border: 3px solid gainsboro;*/
    position: absolute;
    left: 50%;
    top: 50%;
    transform: translate(-50%, -50%);
    background: #ffe3e1;
    -webkit-box-shadow: #666 0 0 6px;
    -moz-box-shadow: #666 0 0 6px;
    box-shadow: #fff8e7 0 0 6px 6px;
    z-index: 996;  /* 此处的图层要大于遮罩图层 */
}